【摘要】 通过在云南省昆明市松华坝水库迤者小流域山坡退化林地设置样地,研究人工干预条件下植物群落与土壤因子特征及其相互关系,旨在为减少该区域水土流失和恢复退化生态系统提供理论依据。选取布设有等高反坡阶的样地和对照样地各3块,在2017年雨季末期对6块样地进行植被调查,计算植物群落多样性,采用模型拟合法对物种重要值进行排序,分析样地植物群落特征;同时按坡位采用三点随机采样法采集0～40 cm表层土壤样品进行土壤因子测定,并结合CCA典范对应分析方法探讨植物分布与土壤因子的关系。结果表明:1)等高反坡阶样地中植物物种Margalef丰富度(1. 09)、Pielou均匀度指数(0. 87)、Shannon-Wiener指数(1. 67)和Simpson指数(4. 49)较对照样地高出2. 51%～9. 00%,其最优种重要值增至25. 49,草本优势种由低矮的禾本科转变为更占生态位空间的菊科。2) 0～40 cm表层土壤总孔隙度(50. 48%)、含水率(20. 45%)、全氮(4. 47 g/kg)、全磷(3. 99 g/kg)和速效钾(67. 64 mg/kg),较对照样地均有所提高。3)土壤密度、总孔隙度、含水率、有机质、全氮以及全磷质量分数是影响山坡退化林地植物群落组成的关键环境因子,布设等高反坡阶7年后,土壤密度和总孔隙度的改变可能是不同样地间植物群落表现出差异的原因之一。总体来说,积极的人工干预措施,在时间尺度下能通过改变土壤因子,进而改变植物群落组成,促进退化生态系统的正向演替。更多还原

【Abstract】 [Background]The water resource area of Songhua dam is an important drinking water source in Kunming City,13 km northeast of the main city,located at 102°45’-102°59’ east longitude,25°08’-25°27’ north latitude,and the drainage area is 629. 8 km2,which guarantees more than 50% of the daily water supply in major cities in Kunming. The area is located in the eastern plateau,and 93. 5% of the land area is mountainous and semi-mountainous,with an altitude of over 2,000 meters. The water conservation forests in mountainous areas are mostly single forest structures,built in the mid-1980 s. The degradation of woodland area in protected areas now seriously affects the function of water resources protection. The contour reverse-slope terrace is an important manual intervention to regulate slope runoff.Then,under the long-term influence of this kind of artificial intervention,how will the secondary forest community structure and soil factors change? How will their relationship change? Understanding the relationship between the two under long-term manual intervention will help us evaluate the role of contour reverse-slope terraces scientifically,prevent water and soil loss and restore water conservation functions effectively in water resources. [Methods] This study was carried out in degraded woodland of Yizhe watershed in the Songhua dam. Three plots with contour reverse-slope terrace and three plots as a comparison were selected. Vegetation surveys were carried out on six plots at the end of the rainy season in 2017. The plant community characteristics of the plots were analyzed,after the plant community diversity was calculated and the important values of the species were sorted by model fitting method. At the same time,the soil samples of 0-40 cm surface soil were collected by three-point random sampling method according to the slope position. The canonical correspondence analysis( CCA) method were used to analyze the changes of soil environmental factors and plant community composition, and the corresponding qualitative relation. [Results]1) Under the condition of long-term artificial intervention,the plant species Margalef richness( 1. 09),Pielou evenness index( 0. 87),Shannon-Wiener index( 1. 67) and Simpson index( 4. 49) were 2. 51% to 9. 00% higher. Among them,the important value of the best species increased to 25. 49,and the herbaceous dominant species changed from Gramineae to Compositae,resulting in an increase in niche. 2) The presence of contour reverse-slope terrace resulted in the increasing of total soil porosity( 50. 48%),water content( 20. 45%),total nitrogen( 4. 47 g/kg),total phosphorus( 3. 99 g/kg) and available potassium( 67. 64 mg/kg). 3) Soil bulk density,total porosity,water content,organic matter,total nitrogen and total phosphorus were key environmental factors affecting the plant community structure of degraded forest land. Seven years of completing the contour reverse-slope terrace,the changes in soil bulk density and total porosity may be one of the reasons for the changes in plant community structure. [Conclusions] In general,the active artificial intervention measure may increase the vegetation diversity and the important plant value by improving soil bulk density and total porosity under the time scale,thereby promoting the degraded ecosystem to positive succession.更多还原